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ALSA plugins

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  ALSA plugins Miroslav Skoric <skoric@uns.ac.rs> - 2021-11-21 21:20 +0100
    Re: ALSA plugins Georgi Naplatanov <gosho@oles.biz> - 2021-11-21 21:50 +0100
      Re: ALSA plugins Miroslav Skoric <skoric@uns.ac.rs> - 2021-11-22 13:10 +0100
    Re: ALSA plugins Dan Ritter <dsr@randomstring.org> - 2021-11-22 01:30 +0100
      Re: ALSA plugins Miroslav Skoric <skoric@uns.ac.rs> - 2021-11-25 16:30 +0100
        Re: ALSA plugins Dan Ritter <dsr@randomstring.org> - 2021-11-25 16:40 +0100
        Re: ALSA plugins Andrei POPESCU <andreimpopescu@gmail.com> - 2021-12-05 13:00 +0100

#242312 — ALSA plugins

Hi all,

I was recently told that ALSA doesn't normally allow sharing a soundcard 
with two applications, but there are two ALSA plugins, dsnoop and dmix 
to share capture and playback respectively. I spent some time in 
searching the web for possible info on how to install or how to check if 
those plugins are installed, but did not find instructions. Any pointer 
in that direction? Thanks in advance.

Misko

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#242315

On 11/21/21 20:57, Miroslav Skoric wrote:
> Hi all,
> 
> I was recently told that ALSA doesn't normally allow sharing a soundcard
> with two applications, but there are two ALSA plugins, dsnoop and dmix
> to share capture and playback respectively. I spent some time in
> searching the web for possible info on how to install or how to check if
> those plugins are installed, but did not find instructions. Any pointer
> in that direction? Thanks in advance.
> 

Why don't you use PulseAudio or maybe PipeWire?

Kind regards
Georgi

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#242323

On 11/21/21 9:33 PM, Georgi Naplatanov wrote:
> On 11/21/21 20:57, Miroslav Skoric wrote:
>> Hi all,
>>
>> I was recently told that ALSA doesn't normally allow sharing a soundcard
>> with two applications, but there are two ALSA plugins, dsnoop and dmix
>> to share capture and playback respectively. I spent some time in
>> searching the web for possible info on how to install or how to check if
>> those plugins are installed, but did not find instructions. Any pointer
>> in that direction? Thanks in advance.
>>
> 
> Why don't you use PulseAudio or maybe PipeWire?
> 
> Kind regards
> Georgi
> 
> 

My issue is related to some amateur radio applications, and the 
application maintainer suggested me to check with ALSA plugins first. It 
should be possible to try PulseAudio as an alternative method but I wait 
for instructions from hams who made it working.

Thanks anyway,

Misko

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#242319

Miroslav Skoric wrote: 
> Hi all,
> 
> I was recently told that ALSA doesn't normally allow sharing a soundcard
> with two applications, but there are two ALSA plugins, dsnoop and dmix to
> share capture and playback respectively. I spent some time in searching the
> web for possible info on how to install or how to check if those plugins are
> installed, but did not find instructions. Any pointer in that direction?

The dmix plugin is installed by default.

$ aplay -L|grep dmix
dmix:CARD=HDMI,DEV=3
dmix:CARD=Generic,DEV=0

The dsnoop plugin is installed by default:
$ arecord -L|grep dsnoop
dsnoop:CARD=Generic,DEV=0
dsnoop:CARD=Generic,DEV=2

You configure them either in your systemwide /etc/asoundrc, or
your personal ~/.asoundrc

-dsr-

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#242400

On 11/22/21 1:04 AM, Dan Ritter wrote:

> 
> The dmix plugin is installed by default.
> 
> $ aplay -L|grep dmix
> dmix:CARD=HDMI,DEV=3
> dmix:CARD=Generic,DEV=0
> 
> The dsnoop plugin is installed by default:
> $ arecord -L|grep dsnoop
> dsnoop:CARD=Generic,DEV=0
> dsnoop:CARD=Generic,DEV=2
> 
> You configure them either in your systemwide /etc/asoundrc, or
> your personal ~/.asoundrc
> 

Thanks. Here is what I got before adding a secondary sound-card device:

ham@localhost:~$ aplay -L|grep dmix
dmix:CARD=Intel,DEV=0
ham@localhost:~$ arecord -L|grep dsnoop
dsnoop:CARD=Intel,DEV=0
ham@localhost:~$


... and here is what I got after adding the secondary sound-card device:

ham@localhost:~$ aplay -L|grep dmix
dmix:CARD=Intel,DEV=0
dmix:CARD=Audio,DEV=0
ham@localhost:~$ arecord -L|grep dsnoop
dsnoop:CARD=Intel,DEV=0
dsnoop:CARD=Audio,DEV=0
ham@localhost:~$


Btw, there was no ~/.asoundrc in personal directory, and also no 
/etc/asoundrc (either before or after attaching the second card). Each 
sound card works well on its own, running different amateur radio 
protocols. The plan is to make the second card 'sharing' its function in 
between the protocol (application) it uses now *and* another one 
protocol that shall be also sent to the same card. However, up to now 
that added protocol/application returns an error msg telling that either 
record or playback device is already busy or not accessible in that card.

And then someone suggested me to check for dmix and dsnoop, as those 
plugins shall overcome that 'application sharing' issue.

Any idea?

Misko

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#242401

Miroslav Skoric wrote: 
> On 11/22/21 1:04 AM, Dan Ritter wrote:
> 
> ... and here is what I got after adding the secondary sound-card device:
> 
> ham@localhost:~$ aplay -L|grep dmix
> dmix:CARD=Intel,DEV=0
> dmix:CARD=Audio,DEV=0
> ham@localhost:~$ arecord -L|grep dsnoop
> dsnoop:CARD=Intel,DEV=0
> dsnoop:CARD=Audio,DEV=0
> ham@localhost:~$

That's good.

> Btw, there was no ~/.asoundrc in personal directory, and also no
> /etc/asoundrc (either before or after attaching the second card). Each sound
> card works well on its own, running different amateur radio protocols. The
> plan is to make the second card 'sharing' its function in between the
> protocol (application) it uses now *and* another one protocol that shall be
> also sent to the same card. However, up to now that added
> protocol/application returns an error msg telling that either record or
> playback device is already busy or not accessible in that card.
> 
> And then someone suggested me to check for dmix and dsnoop, as those plugins
> shall overcome that 'application sharing' issue.

Next you need to tell your applications to use the dmix devices
instead of their defaults.

This is application-specific; read the manual and look for "ALSA
device".

-dsr-

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#242686

[Multipart message — attachments visible in raw view] — view raw

On Jo, 25 nov 21, 15:28:45, Miroslav Skoric wrote:
> 
> And then someone suggested me to check for dmix and dsnoop, as those plugins
> shall overcome that 'application sharing' issue.

As far as I recall the dmix plugin (don't know about dsnoop) has some 
limitations on sampling rates it can work with, which will result in 
resampling in case your card doesn't support that exact sampling rate.

This may or may not be important for your application.

Kind regards,
Andrei
-- 
http://wiki.debian.org/FAQsFromDebianUser

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